A major area of application of the tube bundle is in shell-and-tube heat exchangers. A shell-and-tube heat exchanger comprises a cylindrical vessel internally provided with a tube bundle comprising a plurality of parallel tubes that extend in longitudinal direction of the vessel, wherein the tube bundle further comprises axially spaced apart transverse supports for supporting the tubes in the cylindrical vessel.
As is well known, the shell-and-tube heat exchanger is an indirect heat exchanger in which heat is transferred between a fluid passing through the tubes of the tube bundle (the tube side) and a fluid passing through the space outside the tubes (the shell side). Details concerning shell-and-tube heat exchangers can be found in resources such as Perry's Chemical Engineers' Handbook, 5th edition, 1973, McGraw-Hill Inc., page 11-3 to 11-21. The tube bundle is the most important part of the heat exchanger. The ends of the tubes are secured to a tube sheet. The heat exchanger can include two tube sheets, one at each end of the cylindrical vessel, or a single tube sheet at one end of the cylindrical vessel in the event the heat exchanger is a U-tube exchanger.
It will be understood that the intermediate portions of the tubes have to be supported for purposes such as the prevention of damage to the tubes due to vibrations caused by the fluid flow. To support the intermediate portions of the tubes, the tube bundle includes axially spaced apart transverse supports. A conventional support is a baffle, and there are several kinds of baffles discussed in Perry's. Baffles not only support the tubes, but, because they restrict the flow area in the shell side, baffles also control the fluid flow through the shell side. Therefore, the design of a baffle is determined by heat-transfer considerations as well as for use as a support.
U.S. Pat. No. 2,018,037 discloses a tube support that is designed to reduce the restriction of the flow area in the shell side. This publication discloses a tube bundle comprising a plurality of parallel tubes and axially spaced apart transverse supports for supporting the intermediate portions of the tubes in a cylindrical vessel, wherein the transverse supports consist of rods or bars arranged in lanes between the rows of tubes. A transverse support consists of a support ring that has an outer diameter that is somewhat smaller than the inner diameter of the cylindrical vessel and parallel rods or bars that are secured at their ends to the support ring. When the tubes of the tube bundle are arranged on a triangular pitch (wherein the tubes are so arranged that their centers are on the corner points of equilateral triangles), a set of three axially spaced apart transverse supports arranged at angles of 60° between them will suffice to support the tubes in all directions. And when the tubes are arranged on a square pitch (wherein the tubes are so arranged that their centers are on the corner points of squares), a set of two axially spaced apart transverse supports arranged at angles of 90° between them will suffice to support the tubes in all directions.
Because the known transverse supports consist of a support ring and parallel rods or bars secured thereto, it is not easy to manufacture the tube bundle provided with the known transverse supports.
A particular application of tube bundles is in chemical reactors comprising a tube bundle in a shell, such as those used in the production of ethylene oxide. A very open tube support structure is often required in such a setting. A transverse support for this application is for example known from U.S. Pat. No. 5,366,188. The known support is made from a solid disk that is perforated in a specific way. Manufacturing of such perforated discs is rather expensive.
It would be beneficial to have a tube bundle that is inexpensive and easy to manufacture.